Electric switch



May 21, 1945- C G. M. HAUSLER i` 2,400,754

ELECTRIC SWITCH Filed Jan. 3, 1944 Figi.

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' opposite end of the resilient switch plate.

Patented May 21, 1946 ELECTRIC SWITCH George M. Hausler, Ballston Lake,N. Y., assig'nor to General Electric Company, a corporation of New YorkApplication January 3, 1944, Serial No. 516,753

(Cl. 20D-f6?) 1 Claim.

My invention relates to electric switches, and particularly toovercenter snap-action electric switches having' means for` preventingor inhibiting contact rebound and consequent arcing. The invention isespecially applicable to snap action switches of the bridging contacttype and provides means for utilizing such a switch as a double-polesingle-throw switch, either normally open or normally closed, having itsmovable contacts permanently connected together.

It is a general object of my invention to provide a simple and reliablesnap-action switch of the above character which is adaptable toproduction in small sizes and in considerable quantity.

It is a further object of my invention to provide new and novel meansfor inhibiting rebound of a transversely movable snap-action electriccontact arm.

It is a particular object of my invention to provide new and novel meansfor connecting an overcenter electric bridging contact for use as adouble-pole single-throw electric switchmember.

By way of illustrating one form which my invention may take, I havechosen to show the invention applied to a snap-action electric switch ofthe type described and claimed in my Patent 2,332,911, issued on October26, 1943. As applied to a switch of the type illustrated in theforegoing patent, the invention comprises a relatively light cantileverspring fixedly mounted at one end upon one of the xed contacts andhaving at its other end a hooked portion bent over loosely to embracethe movable contact member at he is light cantilever spring may be usedvas an electric connector to convert the overcenter switch of my priorpatent to a normally open or normally closed double-pole single-throwswitch with movable tips connected common and known to the trade as athree point switch. The 4light cantilever spring has the furtheradvantage that it substantially entirely eliminates-rebound of themovable contact embraced by the free end of the spring.

For a more complete understanding of my in-` 4 sitions of a snap-actionelectric switch embodying another form of my invention.

Referring now to the drawing, I have illustrated a push-button actuatedsnap-action electric switch mounted in a casing IU, lpreferably formedof a suitable molded insulating compound and provided with a removablecover IIla. The

cover Illa may be held in place by one or morebolts Illb shown atFig. 1. The switch member itself is formed of a unitary flat strip orplate II of spring material slotted at I2 and I3 to provide a pair ofouter tension arms I4 and I5 and a central pair of opposing compressionarms I6 and I'i. The compression arms I6 and I1 aredeformable and areformed by dividing the central portion of the plate transversely in theregion of its center, so that the adjacent inner ends of the anus I6 andI1 are juxtaposed in spaced relation.

At its opposite outer ends the resilient plate II carries a pair ofmovable contacts I8 and I9.

Two pairs of fixed stop members 20 and 2| are disposed in spaced-apartrelation adjacent the movable contacts I8 and I9, respectively, forengagement with the movable contacts to limit their movement in oppositedirections transversely of the plate II. At least one of each pairloffixed stop members 20 and 2l constitutes a xed contact cooperating withthe movable contacts I8 and I9. In the form of the invention illustratedin the drawing at Figs. 2 and 3, the upper stop member of each pair offixed stops is an electric contact member and the lower stop of the pairof stops 2i is likewise utilized as an electric contact. In thisparticular embodiment of the invention the lower of the pair of stops 20functions mechanically only and serves no electrical function. In theform of the invention illustrated at Figs. 4 and 5, only the upper stopof the pair of stops 2 I is not used as an' electric contact.

The resilient bridging contact plate Il isl mounted upon an actuatingand supporting member comprising a shank portion or rod 30, and at-`tached push-button or head portion 3I and a pair of bowed spring strips32. The actuating rod 30 is normally biased to its uppermost posi-`tion, as viewed in the drawing, by a compression spring 33. As describedin my Patent 2,332,911, the bowed spring strips 32 frictionally connectthe push-button 3l to the rod 30 and are notched at their lowerjends toprovide y.for pivotal connection to the adjacent inner ends of thecompression members I6 and Il. The notched ends of the spring strips 32thus provide a pivotal supporting and actuating connection between theactuating member` 30, 3|,

32 and the resilient v spring plate or switch member II. 'I'he normalspacing between the pivotal notches at the lower ends of the bowedspring strips 32 is greater than the space between the adjacent ends ofthe compression members |6 and I1 in the plane of the tension members I4and I5. Thus, the springs 32 spring 33 and in the other direction by aperipheral flange 36 upon the push-button head 3|. The iiange 32 isarranged to engage a portion of the casing to determine the uppermostlimit of movement of the actuating rod 30. It will be understood from myprior patent that overcenter movement of the compression members in onediretion causes the tension members I4 and I5 and the movable contactsI8 and I9 to move with a snap action in an opposite direction andlongitudinally of the direction of .motion of the actuating rod.

Referring now particularly to Figs. 2 and 3, I provide a very light orfragile cantilever spring 40 mounted at one end upon the lower fixedcontact 2| and extending in substantially parallel spaced relation withthe switch plate and into loose engagement with the opposite end of theplate II. Thefree end of the cantilever spring 40 is turned over toprovide a hooked or U- shaped end portion 4| loosely embracing themovable contact I8 at the opposite end of the switch plate I I. Byreason of the loose connection between the contact I8 and the free endof the spring 40, a. certain degree of lost motion between the spring 40and the movable contact is provided. The cantileverspring 40 ispreferably vformed of silver or other resilient electric conductingmaterial and is appreciably weaker than the spring plate I I.

It may now be observed that with the snapaction switch in the normalposition shown at Fig. 2, the light spring 40 is merely interposedbetween the movable contacts I8 and I9 and the lower fixed contacts 20and 2 I, thus acting as an auxiliary bridging contact member. When thepush-button 3| is depressed, as at Fig. 3, to move the switch member I Iupward with a snap-action so that the movable contacts I8 and I9 arebrought into engagement with the upper fixed contacts 20 and 2|, theturned-over end 4| of the cantilever spring 40 is interposed between theupper xed contact 20 and the movable contact I8. Thus, the upper fixedcontacts 20 and 2| are electrically connected by the bridging contactplate I and are also connected to the lower fixed contact 2| through theelectrically conducting cantilever spring 40. The switch illustrated atFigs. 2 and 3 therefore constitutes a normally open double-polesingle-throw switch having its movable contact members I8 and I9permanently .connected together and to the common lower xed contact 2 I.

As illustrated at Figs. 4 and 5, the cantilever leaf spring of myinvention may be arranged to transform the snap-action switchillustrated into a normally closed double-pole single-throw switch. Forthis purpose, the spring B0 is perl stationary contacts 20 and 2|.

manently connected at one end to the upper xed When the pushbutton 3| isdepressed to raise the switch plate to its upper position, asillustrated at Fig. 5,

the circuit is broken between the lower stationary contact members andbetween each of these stationary contact members and the upperstationary contact 20.

The light cantilever leaf spring of my invention serves not only toprovide a convenient means for effecting various electrical connectionsof the snap-action switch illustrated, but functions also to inhibitrebound of the movable contact embraced by the hooked free end of thelight cantilever spring. Since the resilient bridging contact platemoves overcenter with a snap action, some rebound of the moving contactsmight normally be expected. It has been observed, however, that the leafspring 4U substantially fully prevents bounce of that moving contactembraced by the free end of the spring. Such non-bounce operation isbelieved to result from the inertia of the spring 40 and the looseconnection between this spring and the moving contact.

The snap-acting switch illustrated in the drawing may be used in stillanother way to take particular advantage of the non-bouncecharacteristic of the switch. Referring by way of example to Fig.v 2,le't it be supposed that the lower stationary contact stop 20 isprovided with an external terminal connector such as those shownattached to the other contacts. If now, the switch is used simply tomake and break the circuit between the lower stationary contacts 20, 2I, it will be observed that the circuit is made and broken only betweenthe free end of the cantilever spring Ml and the lower stationarycontact 2U. The spring 40 is as effective in preventing bounce at thelower contact 20 as at the upper contact 20. Thus, when the switch isused in this manner, arcing is prevented both upon circuit making andcircuit breaking operation. The switch of Figs. 4 and 5 could of coursebe similarly used to make and break a circuit between the upper xedcontacts 2|) and 2 In the form of the invention illustrated, only asingle cantilever leaf spring is provided, so that rebound of only onemovable contact is inhibited. If it is desired to prevent rebound ofboth moving contacts, an additional fragile cantilever spring l nection,it is sufficient to restrain bouncing of any one of the movable contactsupon opening of the switch in order that arcing be eliminated.

While I have illustrated only certain preferred embodiments of myinvention by way of illustration, many modifications will occur to thoseskilled in the art, and I therefore wish to have it understood that Iintend in the appended claims to cover all such modifications as fallwithin the true spirit and scope of my invention.

What lf claim as new and, desire to secure by Letters Patent of theUnited States is:

A snap-action electric switch comprising a. base, a resilient plate ofspring material slotted longitudinally to provide a plurality ofsubstantially parallel arms connected together at opposite outer ends ofsaid plate, one of said arms being divided transversely intermediate itsends to profor moving said compression. members overeenter with respectto the plane of said plate, a pair of movable contacts carried atopposite ends of said plate, a pair of spaced xed contact membersadjacent each of said movable contacts for limiting` transverse movementof said plate in both directions, and a relatively fragile electricconducting cantilever spring mounted at one end upon oneof said xedcontact members and being formed at its other-'end to provide a.U-shaped hook portion loosely embracingthe movable contact at theopposite end of said resilient plate, said cantilever spring stripextending in substantially parallel spaced relation to said plate.

GEQRGE M. 'HAUSLERl

